Gnashing time of T rex revealed

Just as in the film Jurassic Park, Tyrannosaurus rex could bite - hard. A dispute between dinosaur experts has been resolved by scientists in California who have shown the 20-foot carnivore had jaws easily powerful enough to rip apart a struggling triceratops, for example.

For many, T rex is the epitome of the terrifying dinosaur, but some palaeontologists said its tiny arms meant it must have scavenged rather than hunted. Others said its teeth and jaws did not look strong enough to tear apart a live victim.

But Gregory Erickson and colleagues at the University of California at Berkeley put the dinosaur's teeth to the test. They found the bones of a triceratops killed 70 million years ago by a tyrannosaur and made impressions of the tooth marks using dental putty, which they used to get casts of a T. rex tooth. They were serrated like the giant carnivore's, and curved backwards.

However, it was not immediately obvious whether those were enough to finish off other animals. "The triceratops bones were spongy and wasn't clear whether it took a strong bite to do this," said Prof Erickson, whose work is published today in the Nature science journal .

He found that a cow's pelvis was similar in strength and structure to a triceratops's, so he put one in a mechanical loading frame, made a model of the tyrannosaurus teeth and pushed them into the bone to the same depth as the indentations found in the triceratops.

The loader measured the stress required, which, Prof Erickson said, was very large. "It's more force than you see in any animal tested to date, which includes lions and sharks." But Prof Erickson said the findings still do not prove that T rex was a bold hunter as opposed to a craven scavenger. "I think what we need to do is find bite marks like when big cats like cougars attack prey. If you were to find bite marks on dinosaurs from T rex from some sort of a killing bite like this, then you could say it was a predator."